Abrading apparatus



June 13, 1944. w. L. KEEFER I ,3

ABRADING APPARATUS Filed July 23, 1941 3 Sheets-Sheet 1 Wcz/zfefL/feefer Mum aw ABRADING APPARATUS v Filed July 23, 194i 3 Sheets-Sheet2 V I qll' 27 W S r /4 WWW I? Wa/ter A. me r l 75 MJWMW June 13, 1944.w. KEEFER ABRADING APPARATUS Filed July 23, 1941 3 Sheets-Sheet :s'

Wa/zer L. Keefer 90mm X W Patented June 13, 1944 UNITED STATES PATENTOFFIQE' ABRADIN G APPARATUS Application July 23, 1941, Serial No.403,720.

12 Claims.

This invention relates to abrading apparatus and more particularly to acentrifugal wheel for projecting abrasive such as steel grit and shot atan abrading velocity upon workpieces to be cleaned,

Machines of the type herein described may be said to consist of threemain parts, namely, a rotor including one or more abrasive propellingblades thereon, an abrasive supply means, and a transfer mechanism whichfunctions to transfer the abrasive from the supply means to the blade,or blades, on the rotor in such manner that the abrasive is dischargedonto the inner ends of the blades at a predetermined point or zone, theabrasive subsequently being discharged from the ends of the blades in apredetermined zone.

It has been proposed heretofore to provide a transfer mechanism havingan abrasive opening for each blade, the several passages beingmaintained closed by mechanically operated valves except at apredetermined point in the rotation of the transfer mechanism Where themechanical means opens the valves and releases the abrasive onto theadjacent blade. Such prior devices have been characterized by thedisadvantage of pivoted valves and mechanical operating means thereforwhich are susceptible to'rapid deterioration by the abrasive particles.Such prior devices have also required additional means to impart thenecessary velocity to the abrasive which is desirable to secure moreconcentrated blasts and better directional control in any desireddirection of discharge.

In providing an improved centrifugal wheel of the valved transfer type,it is an object of this invention to provide a novel valved transfermechanism of relatively simple construction wherein pivoted valves andoperating means therefor are eliminated, there being no mechanical meanssusceptible of damage by the abrasive.

Still a further object of this invention is the provision of a novelvalved transfer mechanism wherein advantage is taken of the alreadypresent propelling blades of the rotor to both rotate the transfermechanism and to operate the valve means thereof.

A further object of this invention is the provision of a novelcentrifugal wheel employing a valved transfer means wherein the abrasivereceived thereinv may be discharged at any predetermined point and inhighly concentrated charges without the necessity of so-calledadditional impelling or agitating means.

Still a further object of this invention is the valved transfer typewherein the parts are of rel-. atively simple construction, of longerlife, and are easily accessible for replacement and repair.

Further objects and advantages of this invention will appear from thefollowing description and claims, taken in connection with the attacheddrawings, wherein:

Figure 1 is a central section through a centrifugal wheel representing apreferred embodiment of the invention taken on the line l-l of Fig. 2-.

Fig. 2 is a section taken on the line 2-2 of Figure 1 through thetransfer mechanism, theremaining portion of the wheel including therotor and the blades thereon being shown in elevation.

Fig. 3 is a section taken on the line 3'--3- of Fig. 2 illustrating anauxiliary means for communicating rotation of the rotor to the transfermechanism.

Fig. 4 is a front elevation of the abrasive supply means and thesupporting means for the transfer mechanism and 'the means whereby themechanism can be adjusted to change the discharge of the abrasive fromthe periphery of the wheel from one point or zone to another point orzone. I

Fig. 5 is a front elevation of the combined impeller and transfermechanism of Figures 1 and 2.

Fig. 6 is a perspective of one of the valve menibers employed in theimpeller of Fig. 5.

Referring, to Figure 1, the centrifugal wheel there shown is mounted inconventional manner on a shaft H mounted in suitable bearings andarranged to be rotated by suitable driving means such as an electricmotor (not shown). The wheel is enclosed in a housing in conventionalmanner, one wall of the housing beingshown at E2 with a wear plate I3-secured. thereto to protect the housing against wearfrom. the flyingabrasive. It is to be understood that: the housing has one side open,usually at the. bottom or side, through which the. abrasive, such assteel shot and grit, is discharged onto the workpiece to be blasted. i v

A rotor proper It is supported on the end of shaft I l forrotationtherewith by a flange l 5, the rotor proper including a. discit, a plurality of sector plates ii, and one or more abrasive propellingblades I8; Sector platesv I! are detachably secured to the facie'of discIfiby; suitable fastening means, the edges of the secton pl tes beingspaced apart and theiradjacent ed es, beveled so that theycooperate-with the face of disk Iii to define radial extendingdovetail-shaped provision of a novel centrifugal wheel of the 55grooves. Blades [8 are providedwith correspondingly dovetail-shapedbases which fit Within the aforementioned grooves. For a furtherdescription of the sector plates and the manner of holding the blades inposition upon the face of the rotor disk, which does not form a part ofthe present invention, attention is called to United States Patent No.2,246,522, issued June 24, 1941.

The disk US may extend completely across flange I5, but it is preferredto provide an opening in the center of the disk to receive a dishedplate or retainer |9 secured therein by a bolt 2| entering flange l5.Retainer I9 is provided with a circumferential, axially extending flange22 that functions to help retain the valve members in the impeller in amanner to be described.

Each blade |8 includes a propelling surfac 23 onto which the abrasive isdischarged and side flanges 24 and 25 which prevent the abrasive fromescaping sidewise from the propelling surface. spaced from the inner endof the blade to leave a flangeless extendingportion 26 which functionsin the valving of the abrasive from the impeller in a manner to b laterdescribed.

The abrasive supply means or feed means includes a feed spout 21 intowhich abrasive is fed, as by gravity, from ahopper positioned above thewheel. For support, feed spout 21 is formed with a flange 28 at itsupper end having holes 29 therein which fit over pins 3| projecting froman angle bracket 32 secured to wall |2 of the hous- An opening 33 isprovided in wall l2 and wear plate |3 into which is fitted a holder 34having a cylindrical section 35 and a flange 3-6 which fits against theoutside of wall |2. Studs 31 are mounted in wall |2 to receive clamps 38engaging flange 36. By this arrangement, holder 34 can be rotated to anydesired position and clamped therein, suitable nuts being threaded onstuds 31 to secure the clamps.

To center the holder 34 and insure its so remaining, three studs 39 aremounted in wall |2 with small cams 4| and nuts 42 thereon. By rotatingcams 4| which contact the outer periphery of flange 36, the holder canreadily be centered, the cams thereafter being locked by nuts 42 andpreferably welded in position to insure against their becoming loosened.V

Adjacent its center, holder 34 is formed with a shouldered opening 43into which is telescopingly fitted a circular section 44 on the lowerend of feed spot 21. A gasket 45 is preferably provided in lcoonnectionwith the telescoped parts to prevent the leakage of abrasive around thejoint thus formed.

The lower end of spout 21 is provided with a flange 46 adjacent a bolt41, secured in holder 34, and mounting a clamp 48. When holder 34 is tobe rotated to a new position, bolt 41 is loosened and subsequentlytightened after holder 34 has been adjusted. To enable clamping whenholder 34 is rotated as much as 180, or even less, holder 34 may beprovided with other tapped holes to receive bolt 41. This arrangementinsures proper support of the lower end of the feed spout in allpositions of holder 34;

The holder 34 is formed with a projecting central section or boss 49which is recessed at 5| to form a passage 52 connecting with thedischarge end of feed spout 21 and serving as a continuation thereof.Passage 52 is preferably shaped in cross-section, as shown in Fig. 2,the wall defining the right side, as viewed in Fig. 2, being somewhatshortened and rounded as at 53 to facilitate Flanges 24 and 25 terminateat a point the discharge of abrasive in the direction in which the wheelrotates, or counterclockwise, as viewed in Fig. 2. It will be noted thatin the abrasive feed passage defined by the feed spout 21 and thepassage 52, there are no abrupt bends to hinder the flow of abrasive,the latter being able to flow into the transfer means in a substantiallystraight and unobstructed path.

The boss 49 is bored on an axis offset from or eccentric of the axis ofrotor l4 to support one end of a shaft 54 which is flanged at 55 to fitwithin a recess 55 in the end of the bore. To insure shaft 54 remainingin a fixed position in its bore, it is preferably welded therein asshown at '51, the left end of the shaft (Fig. 1) being shaped to conformto the contour of passage 52 and maintain a free unobstructed passagefor the abrasive.

The shaft 54 is provided with a bearing 51a upon which is supported ahub 58 of a cage-like member or impeller 59, hub 58 being of truncatedconical shape to fit within the concave end of boss 49. Hub 58 ispreferably reinforced by ribs 60 and is formed with a flange 6| whichsupports a series of circumferentially arranged elements 62, each ofsaid elements defining an abrasive passage 63 with th next adjacentelement, said passages leading to the exterior of the impeller.

While element 59 is referred to as an impeller, it is to be understoodthat it serves also as means for effecting the discharge of abrasiveonto the inner ends of the rotor blades at a predetermined point. Byreason of its double function as hereinafter explained, the singleelement can be employed to discharge abrasive at any selected pointaround its periphery ata considerable velocity without the need of anyadditional agitating or abrasive impelling means. I

On its leading face, each element 62 is formed with a substantiallyradial short face 64 merging into a forwardly curved surface'65 whichterminates in an abruptly reversed surface 66.

The trailing face of each element 62 is formed by an outwardly andrearwardly inclined surface 61, preferably formed at an angle of about107 to a radius, leading into a curved surface 68 which continues to asurface '69 at which the abrasive is-discharged. It will be noted thatthe outer end of surface 68 is slightly dished at 10 tofunction asavalveseat. v f

Each element 62 is' formed with a partially cylindrical recess 1|, theouter end of which is partly closed by an inwardly projecting section12, curved on its inner surface to function as a valve seat. Recess 1|is open at both ends of the impeller to permit the ready insertion andremoval of a valve member 13 of cylindrical shape (Fig. 6) and formed ofrelatively. soft material, such as rubber. Y

Adjacent the right end of the impeller as viewed in Fig. 1, and aroundthe periphery, a

series of Webs 14 are provided connecting a porthe impeller is mountedon an axis which is oi'fset with respect to the axis of the disk, theyoke connection with a pin 16 is essential to'permit the eccentrictravel of the impeller.

The inner portions of elements 62 are extended axially from hub 58toward holder 34 where they are connected by a flange 11 which func'--tions to protect the interior mechanism from the action ofthe' abrasiveparticles.

The holder 34- is' formed with a circumferentially projecting flange 18which terminates adjacent the left end of each of valve members 13 toprevent the valve members slipping forward in their seats H, rearwardslippage of the valve members being prevented by flange 22 on retainerI9.

In-operation, the disk I6 is rotated at an abrading speed by the drivemeans connected thereto. The impeller or cage-like member 59 is rotatedat the same speed by reason of the inner ends 26 of blades l8 engagingthe faces 69 of the several passages 63-. This action is analogous tothe drive of an internal gear by an external gear, and prevents theimpeller getting out of synchronism with the disk since one blade tip 26is always driving through contact with a face 69 while the face of asection 12 prevents the impeller from running ahead of the disk. Inevent of the breaking of one or more of the blade tips, continuedrotation ofthe impeller with the disk will be assured by the engagementof pins 16 with yokes 15.

- 'Abrasive fed through spout 21 is discharged in the embodiment showninside the impeller, and

at the bottom thereof. A charge of abrasive S from the end of the feedspout is picked up by the forward face 64 of each element 62, the chargeS continuing along surface 65 by reason of centrifugal force duringcontinued rotation of the impellerand finally discharging therefrom ontosurface 68, and there collecting at S, as shown in Fig. 2. It will benoted that in all these positions of the abrasive that the element 62'bywhich the abrasive is being collected has its valve member 13 in closedposition by reason of centrifugal force, the valve member sealing theopening to the exterior of the impeller by reason of its contact withvalve seats.

Upon reaching the point designated at A in Fig. 2, the inner end 26 ofthe adjacent blade [8 comes into contact with valve 13. With continuedrotation of the blade and impeller, the impeller moves outwardly, theblade moving correspondingly inwardly relative to the abrasive passage63 to a point shown at B wherein the valve member 13 has been pushedinwardly away from its seating surfaces, whereupon the abrasivecollected upon the surface 68 is discharged by centrifugal force ontothe inner end of the blade with considerable velocity.

, Upon continued rotation of the wheel, the

Zchargeofabrasive flows outwardly over the surapproximately 270, theopen range being about 190K. At about the 12 oclock position or aboutthe: point A in the embodiment shown, the blade ends begin to. open thevalves, permitting the abrasive charges to slide out of the passagesonto the. blades, the; abrasive being accelerated to abradi'ng velocityas it moves outward over the vane surface; nt. approximately the :30

The formation of the individual charges of abrasive is as alreadydescribed. By reason of the shapes of the walls of passages 63, thecharges are readily formed and subsequently maintained in: a positionwhere they can be quickly discharged. The opening of the valvesiscomparable to the releasing of one end of a rapidly rotating sling.While the shot in the sling has no movement relative to the sling whilethe latter isbeing slung, it files from the sling at considerablevelocity when the sling is released.v Likewise, while the abrasivecharges, once collected, do not move relative to the impeller while thevalves are closed, they are discharged therefrom at a considerablevelocity when the valves are opened. This velocity results in animproved abrading stream both as to abrading properties and directionalcontrol.

While the embodiment described is a downblast wheel, it is to beunderstood that by rotating holder 34 and changing the point ofeccentricity of the impeller axis, the direction of the stream ofabrasive can be adjusted to the left or right.

Obviously the stream can be caused to discharge at any point in 360 bychanging the point of eccentricity of the impeller axis. It is preferredthat the discharge end of the feed spout at 52 remain in substantiallythe same position regardless of the position of the impeller axis.

The action of the abrasive in passing over the valve seats is notsevere. since at this radius the abrasive velocity is relatively low andthe surfaces 58 are retreating as the abrasive slides thereacross,thereby reducing the pressure of the abrasive. Even with considerablewear on the valve seats, the. valveswill continue to function because oftheir elasticity and ability to conform to irregular surfaces. Actualwear on the valves is. minimized because there is no movement ofabrasive across the valve when it is closed, and

when it is open the valve is thrust inwardly into its semi-cylindricalchamber wherein it is protected from the abrasive.

It is to be understood that the invention may be embodied in specificforms other than that i1- lustrated without departing from the principleor essential characteristics thereof. The embodiments shown aretherefore to be considered as illustrative and not restrictive, thescope of the invention being defined by the appended claims rather thanthe foregoing description and drawings. All modifications and changeswhich come within the'me'aning and range of equivalency of the claimsare therefore intended to be included therein.

I claim:

1. In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner ends of said blades being spaced apart todefine a central opening, means to feed abrasive into said centralopening, and means to transfer said abrasive to the inner ends of saidblades comprising a cage-like memberformed with a passage in itsperiphery adjacent the inner ends of each of said blades, and'valvemeans to normally close each of said passages, said member being mountedto rotate about an axis sufficiently eccentric of said rotor axis tobring the orbit of the inner end of thebladeswithin the orbi't'of saidvalve means to thereby causesaid valve means to be opened by the innerends of said bladesat a predeter mined point. a

2. In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner ends of said blades being spaced apart todefine a central opening, and means to feed abrasive onto the inner endsof said propelling blades comprising a cage-like member arranged torotate at the same speed as said rotor about an axis offset from andparallel to the rotor axis, means to feed abrasive into said member in asubstan tially continuous stream, a series of blades in said memberarranged to divide said abrasive stream into a series of individualcharges, one for each of said blades, and to conduct said charges to theouter periphery of said member, and means to normally prevent thedischarge of said abrasive charges from said member, said latter'meansbeing arranged to be rendered inoperative by said abrasive propellingblades at a predetermined point in the rotation of said rotor.

3. In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner ends of said blades being spaced apart todefine a central opening, means to feed abrasive into said centralopening, and means to transfer said abrasive from said feed means to'theinner ends of said blades comprising a cage-like member mounted torotate at the same speed as said rotor and on an axis displaced withrespect to the'rotor axis receiving abrasive from said feed means, aplurality of openings in the wall of said membenmeans to normally closesaid openings, and means on the inner ends of said blades to render saidlast-mentioned means inoperative at a predetermined point in therotation of said rotor.

4. In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner ends of said blades being spaced apart todefine a central opening, means to feed abrasive into said centralopening, and means to transfer abrasive from said feed means to theinner ends of said blades comprising a cage member mounted to rotate atthe same speed as said rotor, said member having a valvecage in itsperiphery adjacent the inner end of each of said blades, said memberhaving an opening adjacent each of said valve cages leading from theinterior of said member to its exterior whereby abrasive may pass fromthe interior of said member onto the inner ends of said blades, avalvein each of said valve cages arranged to close said openings underthe action of centrifugal force, and means supporting said member on anaxis sufiiciently eccentric of the axis of said rotor whereby the innerend of each blade engages andopens the corresponding valve at apredetermined point in the rotation of said rotor to efieet delivery ofabrasive onto the inner end of said blade at said predetermined point.

In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner ends of said blades being spaced apart todefine a central opening, abrasive feed means extending into saidcentralopening, and means to transfer abrasivefrom said feed means to the innerends of said blades comprising a cage-like member arranged toreceiveabrasive in its interior from said feed means, means on said feedmeans to support said m mber for rotation about an axis eccentric of theaxis ofsaid rotor, said member having an opening in its peripheryadjacent the inner; end of each blade, a valve in each of said e e ar dt 9 6 s id ev n n s und r the action or centrifugal force when saidmember is'rotated, and the inner end of each of said blades beingadapted to engage and open the corresponding valve at a predeterminedpoint in the rotationof said rotor to; permit the delivery of abrasiveonto the inner end of said blade, and .to engage said member to,causethe latter to rotate at the same speed as said rotorh 6. In anabrading apparatus, a rotor having a plurality of abrasive propellingblades, the inner ends of said blades being spaced apartto define acentral opening abrasive-feed means extending into said central opening,and means to transfer abrasive from said feed means to the inner ends ofsaid blades comprising a cage-like member mountedto'rotate at the samespeed as said rotor on an axis displaced from the rotor axis and havinga series of passages extending from the interior to the exterior, therebeing one passage for each of said blades, said feed means beingpositioned to discharge abrasive into said passages at a predeterminedpoint in the rota.- tion of said member, centrifugally operated valvemeans to normally close said passages, and means on the inner ends ofsaid blades to open said valve means at a second predetermined point inthe rotation of said member to permit the feed of abrasive onto theinner ends of said blades I '7, In an abrading apparatus, a rotor havinga plurality of abrasive propelling blades, the inner ends of said bladesbeing spaced apart to define a central opening, abrasive feed meansextending into said central opening, and means to transfer abrasive fromsaid feed means to the inner ends of said blades comprising a cage-likemember mounted to rotate at the same speed as said rotor and having aseries of passages extendingfrofn the interior to the exterior, therebeing onepassage for each of said'blades, an axially extendingopen-ended semi-cylindrical valve cage associated with each of saidpassages, a cylinder of relatively soft material in each of said cages,said cylinder being arranged to maintain said passage closed under theaction of centrifugal force, and means for moving each cylinder to aposition for opening an associated-passage at a predetermined .thepropelling surface of said'blade, a. valve in said passage, and ,meanson the inner end of said blade to engage and open .said valve at'apredetermined point in the rotation of said rotor, said, last mentionedmeans being rearwardly of the point of discharge vof said abrasive.

- 9. In an abrading apparatus, a rotor having a plurality of abrasivepropelling blades, the inner "ends of said blades being spaced apart todefine a central opening,v abrasive ,feed means extend- ,ing into saidcentral openi'ng,.and means to transfer abrasive from said feed meanstothe, inner ends of said-blades comprising a, cage-likemem- ,berarranged to; receive abrasive in. itsinterior {from said feedmeans,means on said feed means to support said member'for rotation about anaxis eccentric of the axis of said rotor, a driving connection betweensaid rotor and said member for rotating the member at the same speed asthe rotor, sai member having a series of passages extending from itsinterior to its exterior, an open-ended axially-extendingsemi-cylindrical valve cage associated with each of said passages, acylindrical valve in each of said valve cages, said valve being arrangedto close said passage under the action of centrifugal force, means onsaid member-supporting means and said rotor to prevent axialdisplacement of said valves, and means for moving each cylindrical valveto a position for opening an associated passage at a predetermined pointin the rotation of said rotor.

10. A transfer mechanism for use with a centrifugal abrading rotorcomprising a cage-like member mountable for rotary movement and having aseries of passages extending from the interior to the exterior, anaxially extending open-ended semi-cylindrical valve cage associated witheach of said passages, a cylinder of relatively soft material in each ofsaid cages, said cylinders being larger than the opening at the outerend of the passages to maintain said passages closed under the action ofcentrifugal force, and said cylinders being movable inwardly to opensaid passages.

11. In abrading apparatus, a rotor, a plurality of abrasive propellerblades on said rotor with the inner ends thereof defining a circularspace concentric with the axis of said rotor, a cage member rotatablymounted in said space on an axis parallel to but displaced from the axisof the rotor and rotating at the same speed as said rotor, said cagemember having a plurality of passages therein, movable means normallyclosing each passage, the eccentricity between said rotor and said cagemember being such that during rotation of the cage member about the axisthereof eccentric movement of the cage member relative to the rotor willurge one of said movable means into engagement with an inner end of oneof said propeller blades to open the associated passage at apredetermined point in the rotation of said rotor.

12. In centrifugal abrading apparatus, a rotor including a plurality ofpropeller blades extending inwardly short of the axis of the rotor, acage member rotatably mounted between the inner ends of said propellerblades on an axis substantially parallel to but displaced from the axisof the rotor, webs on the cage member each having a peripheral recesstherein, and a plurality of pins carried by the rotor arranged tooutline-a circle concentric with the axis of the rotor and adapted toengage said webs Within said recesses to drive the cage at the samespeed as said rotor.

WALTER L. KEEFER.

